<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!--平时使用开发版本-->
    <link rel="stylesheet" href="../static/plugins/bootstrap-3.4.1/css/bootstrap.css">
    <!--要上线时使用生产版本，与开发版本一致，只是被压缩了-->
    <!--    <link rel="stylesheet" href="static/plugins/day12_bootstrap-3.4.1/css/day12_bootstrap.min.css">-->
</head>
<body>
<input type="button"  value="提交" class="btn-danger">
<input type="button"  value="提交" class="btn-success">
<input type="button"  value="提交" class="btn-primary">
<input type="button"  value="提交" class="btn-danger btn-xs">
</body>
</html>